In recent years, due to advances in technology and efficiency, the application of LEDs has become more and more extensive; with the upgrading of LED applications, the market demand for LEDs is also toward higher power and higher brightness, which is known as the development of high-power LEDs. . For the design of high-power LEDs, most of the current large-scale manufacturers mainly use large-size single low-voltage DC LEDs. There are two methods, one is the traditional horizontal structure and the other is the vertical conductive structure. In the first approach, the process is almost the same as the general small-size die. In other words, the cross-sectional structure of the two is the same, but unlike the small-sized die, high-power LEDs often need to operate at high currents. Underneath, a little unbalanced P and N electrode design can lead to serious current crowding. The result is that the LED chip can not meet the brightness required by the design, which will also damage the reliability of the chip. (Reliability). Of course, for upstream wafer makers/wafers, this process has a high CompaTIbility, eliminating the need to purchase new or special machines. On the other hand, for downstream systems, the surrounding mix, Such as the design of the power supply, etc., the difference is not big. However, as mentioned above, it is not easy to spread the current evenly on large-size LEDs. The larger the size, the more difficult it is. At the same time, due to the geometric effect, the light extraction efficiency of large-size LEDs tends to be smaller and smaller. . The second method is much more complicated than the first one. Since the commercialized blue LEDs are almost all grown on the sapphire substrate, the vertical conductive structure must be bonded to the conductive substrate before being electrically non-conductive. The sapphire substrate is removed, and then the subsequent process is completed; in terms of current distribution, since the lateral conduction is less considered in the vertical structure, the current uniformity is better than the conventional level structure; otherwise, the basic In terms of physical processing, materials with good electrical conductivity also have high thermal conductivity. By replacing the substrate, we also improve heat dissipation and lower the junction temperature, which indirectly improves the luminous efficiency. However, the biggest disadvantage of this approach is that due to the increased complexity of the process, the yield is lower than the traditional horizontal structure, and the production cost is much higher. Basic structure and key technology of high voltage light-emitting diode (HV LED) Epistar has pioneered the development of high-voltage LEDs (HV LEDs) as high-power LEDs in the world; its basic architecture is the same as AC LEDs, which are formed by dividing the wafer area into multiple cells and connecting them in series. Its characteristic is that the chip can determine the number and size of its cells according to the demand of different input voltages, which is equivalent to the customized service. Since it is possible to optimize for each cell, a better current distribution can be obtained, thereby improving luminous efficiency. The most important difference in technology between high-voltage light-emitting diodes and general low-voltage diodes is flaws. The first is Trench. The purpose of the trench is to separate a plurality of cells. Therefore, the substrate below the trench needs to be insulated. The depth varies depending on the epitaxial structure. Generally, it is about 4~8um, and the trench width is not certain. The limitation, but the too wide groove represents the reduction of the effective light-emitting area, which will affect the luminous efficiency of the HV LED. Therefore, it is necessary to develop a high aspect ratio process technology to reduce the process line width to increase the luminous efficiency. The second is the insulating layer (IsolaTIon). If the insulating layer does not have good insulating properties, the entire design will fail. The difficulty lies in the fact that the high aspect ratio trench must be coated with good coating, tight film and insulation. A good film layer, which is also the key to the single crystal AC LED process. The third is the interconnect between the wafers. In general, to make a good connection, the wire needs a relatively flat surface when it is bridged. A deep stepped structure will make the wire structure weak, and it will be damaged under high voltage and high current driving, resulting in wafer Failure, so the development of the flattening process becomes important. The ideal state is to flatten the deep trenches when the insulating layer is used, so that the interconnecting wires can be smoothly connected. In addition, the main difference between high-voltage LEDs and general low-voltage diodes is that they can be used not only in constant DC, but also in AC environments as long as external bridge rectifiers are used. Very flexible. In the high-voltage light-emitting diode, the external rectifier discards the AC LED and uses a homogenized gallium nitride instead of a silicon rectifier, which not only consumes less energy, but also prevents the influence of excessive reverse bias on the wafer; Because the high-voltage light-emitting diode has less internal light-emitting area than the AC LED, the luminous efficiency is relatively high, and the durability is also better. As a solution for large size, high power LED The efficiency of the high-voltage light-emitting diode is superior to that of the conventional low-voltage light-emitting diode, which can be attributed to the design of a small current and multi-cell to uniformly spread the current, thereby improving the light extraction efficiency. In some applications, in addition to the efficiency of the chip itself, the price of the final product is also an important indicator; for example, in the current lighting field, the LED light source is still not regarded as a mainstream product, the key point is that its price is still High. The high cost of LED light sources, in addition to the price of the chip itself, the Bill of material (BOM) needs to be considered. For example, since the light-emitting diode is essentially a polar component, it must be supplied. A forward bias is illuminated, so an AC-to-DC power conversion system must be added to the LED lighting source, which is a cost. Moreover, since the LED itself is small in size, the heat source is easily concentrated, and a so-called hot spot phenomenon is caused, so that the life of the light-emitting element itself is shortened. In order to solve the hot spot problem, the heat dissipation design on the LED light source is also indispensable. At present, the metal heat sink is the most common in the heat dissipation design, but the metal heat sink increases the cost of the light source in addition to the weight of the light source. Since the high-voltage light-emitting diode itself is highly efficient, it reduces the waste heat and the need for heat dissipation, thereby reducing the cost; from the perspective of power conversion, a high-voltage small-watt power converter such as a flyback extension servant circuit, in addition to the volume Small outside, because the components used are small, the cost is also low. Therefore, the advantage of the high-voltage light-emitting diode is not only the wafer itself, but also the efficiency of the overall module can be further improved directly or indirectly. In summary, in application and design, single-chip high-voltage light-emitting diodes have the following benefits: 1. Save the loss of transformer energy conversion and reduce the cost. 2. In addition to the application of high voltage DC, the external bridge rectifier circuit can also be designed to operate under AC. 3, small size does not occupy space, has excellent application flexibility for packaging and optical design. 4, in addition to red fluorescent powder, you can also use blue, red HV LED with appropriate yellow, green fluorescent powder to make higher efficiency high CRI warm white LED. At present, in Jingyuan Optoelectronics, the basic inspection of design criteria is first made according to the customer's various parameter requirements; further simulation is carried out according to the relevant optical, electrical and thermal models to determine the size, number and final product presentation of the unit cell. After the form, it is verified by practice; and based on the information collected in practice, verify the design, or modify it to achieve the optimized result. At present, the Jingyuan Optoelectronics R&D Center has begun to establish the simulation of light, electricity and heat models related to high-voltage LEDs. Piezo Buzzer,Micro Piezo Buzzer,Active Piezo Buzze,Passive Piezo Buzzer NINGBO SANCO ELECTRONICS CO., LTD. , https://www.sancobuzzer.com